The present invention generally relates to test equipment, and specifically to test equipment for repetitive thermal cycling between high and low temperatures.
Thermal cycling test equipment, such as environmental test chambers, are commonly used to test products by subjecting them to thermal shock, i.e., rapidly transitioning between high and low temperature extremes with short dwells at each extreme. This type of testing results in inefficient use of a refrigeration system, which operates under high capacity requirements during the rapid cooling cycle and no cooling requirements for other intervals of the testing. To achieve the rapid cooling required, large capacity refrigeration systems relative to the workspace or product load are commonly utilized.
Thermal shock tests were previously performed by physically transporting a test product between separate heating and cooling chambers. The test product was transported by a human operator or a mechanical conveyor. Transport by a human operator created error in transition times between the high and low temperature extremes. Furthermore, movement of the test product created mechanical stresses and caused logistic difficulties if the test product needed to be plugged in, for example.